RC:

 A little correction regarding the ECU type/manufacturer: It is NOT Siemens but Bosch with the ME 7.8.1. 

Sorry about this confusion...

The ME 7.8.1 is similar to the 997 Turbo (pre-facelift), which could be an advantage for tuners. As far as I remember, the 997 Turbo/Turbo S facelift uses the Siemens SDI3 but I'm not 100% sure about it.

 

According to dealers sale material that I got new 991 Turbo/Turbo S use SDI9 digital motorelektronik.